Wobble/vibratgion at speed

[Sledge]

I've recently picked up a wobble or vibration at speed. I don't notice it until I get to about 55 mph, and it is worst and most wobble-like at 55-65. By 75 mph it is smooth as silk; but at 80-100 it is back again as a higher frequency vibration. I haven't taken it over 100. I've had one wheel/tire re-checked for balance but haven't had the others re-checked yet, or the tires checked for "round." They are newish MT Sportsman SR's.

Having looked at previous posts, I have taken all 4 wheels off and reinstalled them carefully so as to get them centered on the lugs. I can not see anything loose or wrong with the front end or steering, and I'll be going under the car when my garage gets below 100 deg to check any looseness in the drivetrain (u-joints, cv joints, etc.).

Any other suggestions besides prayer?

Thanks,

[Cashburn]

That's a typical tire balance issue. Once you verify all 4 are balanced properly see where we are.

[Tommy]

If you can isolate the vibration to one particular corner, swap that wheel/tire with another and see if the vibration moves. If it does and everything else seems right, you might be experiencing tread separation within the tire.

[Bob In Ct]

They're not out of balance, they're not round! Although they may be dimentionally round they may not be dynamically round. You're getting a lesson in harmonics. Those without the problem always think it's a balance issue, it's not. No doubt the car has no "rag joint".

Bob

[Cashburn]

Are you in fact running 15s or 17s? We've managed to run 15s on all our cars with no vibration issues, without a "rag joint". It takes a long time to find a proper shop to balance them correctly though.

If the issue sprung up with the new tires then suspect the tires. If sudden then look for lost weights. If no evidence of lost weights then it gets interesting...

[dcdoug]

Find a shop that can fine tune the balance with the wheels on the car. This way it also includes the rotors as well. Made all the difference on my car (15" wheels with billboards).

Note: Preferrably a shop that works with racers so they really know how to get it exact.

[mtpockets]

We have a local member that bought a High Speed/Road Force balancer. Had the manufacturer rep deliver and teach him the proper way to high speed balance a tire. It takes lots of time and effort to get it right and the results are amazing. High tech, lasers, etc and takes at least 1 hour to balance 4 tires. After balancing or attempting to balance 16 tires one day, 4 tires were classified as BAD tires, could not be balanced.

There are a few tire shops around that have them but the employees a poorly trained on the proper way to use them, add to that they charge you $120 to do 4 tires, avoid them. I had a minor vibration at speed, had all four balanced, big difference. Good luck finding a shop with one of these machines and even better luck finding someone that knows how to use it properly.

[Sledge]

Thanks everyone.

They are new tires (4 or 5 months old, 15-inchers) but the wobble wasn't happening until 3 weeks or so ago. Oh, and no rag joint, what's the thinking on that--good to have, or masks a symptom?

I'll see what I can find in re balancing around here, and then see what happens.

[dcdoug]

Any chance you threw a wheel weight? Are they all there?

[Sledge]

Doug--I guess we'll find out. I've found a local shop that specializes in on-the-car balancing and he'll do that tomorrow. If that doesn't do the trick then the issue of "round" may have to be looked at.

[Sledge]

Success!

Actually, the guys first trued the tires, then did the balancing, all on the car. A dumpy little hole-in-the-wall outfit but highly thought of for their talent. Jay Leno apparently brings some of his collection here for truing and balancing.

Heavy traffic on the freeway so I could only get it up to 85 but there was NO vibration or wobbling. Thank you all for the advice.

[209]

Is this common to M/T Sportsman S/R's?? That was my next set. 209

[Sledge]

I asked the guys at the shop when I picked up my car (I don't know if they deal M/T tires or not) exactly that question, and they said no, it is common to most tire brands. The implication was the M/T's are no worse than anyone else's. Cost was about the same as another SR, mounted and "balanced."

I like the tires esp now that they are round(er).

[D-CEL]

Sledge,

Can you give the name and contact info for the shop.
Im sure some of us could use it LOL

Thanks
JASON

[Bob In Ct]

There's a shop in Bridgeport, CT (Major Racing Traction I think) that "trues" tires. A bunch of years ago I had 4 BFGs done. It made a big difference. Replacing the BFGs with Yokos produced an even bigger improvement.

Remember, even a square can be in balance!

Bob

[Sledge]

http://natejonestires.com/

Don't let the looks of the place fool you, these guys know their stuff.